The invention is directed to a testing device for component equipped printed circuit boards having a lower needle adapter carrying spring-seated, lower contact needles arranged test-specimen-associated for contacting the under side of the printed circuit board and comprising a plurality of upper pressure rams arranged test-specimen-associated.
Needle adapters having contact pins arranged test-specimen-associated are used for the electrical testing of component equipped printed circuit boards, such as logic cards. A distinction is thereby made between a circuit test or a function and sub-function test. During the test, the equipped printed circuit board has its solder side pressed against spring-seated contact needles arranged in the needle adapter. When both a circuit test, as well as, a function or sub-function test are then to be carried out in the same testing device, a two-stage contacting device having contact needles of different lengths is provided. In the first stage of the contacting, only the long contact needles come into engagement during the function or, respectively, sub-function test, whereas the short contact needles are added in the second stage of the contacting during the circuit test.
A simultaneous contacting at the components side of the printed circuit board is not provided in the known needle adapters. In the course of the increasingly prevalent SMT technology, however, this demand for a two-stage contacting is required more and more frequently. Further, the plug connectors can frequently be contacted only from above insofar as one wishes to forego the involved, lateral contacting of the plugs in the function test.
The pressing of the equipped printed circuit boards required for contacting can be mechanically undertaken via correspondingly distributed pressure rams. For example, vacuum adapters are frequently utilized. The equipped printed circuit board is manually placed on a sealing rubber therein and pressed thereagainst by producing a vacuum. Contrasting with the advantage of an improved accessibility to the components side given such vacuum adapters are a number of disadvantages at the same time. Since an optimum metering of the vacuum is not possible, inadmissibly high bending of the printed circuit boards can occur due to the high surface pressure and cannot be reliably avoided. Further, the sealing represents a considerable problem, so that a reliable contacting can frequently only be guaranteed by using additional pressing at specific locations or by other, additional, manual operations. Further, the spectrum of printed circuit boards suitable for testing in vacuum adapters is limited since, for example, open plate-throughs and passages should not be present. In view of the automation of the final testing of equipped printed circuit boards, the problems recited above are even more pronounced. In particular, the contacting reliability would be further reduced by additionally occurring sealing problems given an automatic changing of the printed circuit boards.